1. Field of the Invention
The present invention relates to a stuffing box assembly and, more particularly, to a stuffing box assembly wherein the packing or seal between a movable shaft and the stuffing box through which the shaft extends is energized.
2. Description of the Background
As is well known, in stuffing box assemblies used to seal between a movable shaft, i.e. reciprocating or rotating, and the stuffing box housing, a packing is disposed between the shaft, piston or the like and the wall of a bore in a housing which forms the stuffing box. In order to effect fluid-tight sealing between the stuffing box and the shaft, the packing is axially compressed to bring it into inner and outer radial engagement with the shaft and stuffing box wall, respectively. Most frequently, this is accomplished by means of an adjustable gland which can be advanced into an annulus formed between the shaft and the stuffing box wall and against the packing, the packing being restrained from any substantial axial movement away from the gland by means of a stop, usually in the form of an annular shoulder. In this arrangement, as the packing wears, leakage can occur past the packing, either along the wall of the stuffing box or between the shaft and the packing or between the shaft and the packing. In order to solve this problem, it has been proposed to energize the packing in such a fashion that, as the packing wears, it is continuously axially biased resulting in radially inwardly and outwardly expansion to thereby maintain its sealing efficiency and prevent leakage from one side of the packing to the other.
U.S. Pat. No. 3,982,765 shows a piston pump in which a coil spring is used to energize packing rings disposed between the stuffing box and the shaft. U.S. Pat. No. 3,608,912 shows a seal assembly for a valve stem in which annular, resilient seal members, e.g. O-rings, are received in a pocket formed between a liner which surrounds the valve shaft and an internal, cylindrical wall formed in the neck of the valve. The resilient members shown in U.S. Pat. No. 3,608,912 are employed to exert a radially inward force against the liner sleeve and are not used as an energization method for an axially displaced seal, e.g. packing rings.